Water heaters can provide for the heating and storage of water to be used in e.g., a residential or commercial structure. A typical construction includes a water tank that is surrounded by a jacket and is insulated. A heat source is provided for increasing the temperature of water in the tank. The heat source is commonly based on e.g., gas burners or electrically-resistant coils.
In such constructions, heat created from combustion or the resistance to a current flow is provided directly to the water tank. With gas burners, for example, the burner is located just below the bottom wall of the water tank. Combustion of a liquid or gaseous fuel provides heat that is conducted through the wall of the water tank. In the case of electrically-resistant coils, one or more such coils are typically inserted through a wall of the tank and into the water. Heat generated by the resistance to current flow is transferred to the water.
While substantial improvements have been achieved, there is still a need for improvement in water heater efficiency.
One technology that has been proposed for improving water heater efficiency is the use of sorption based water heaters. For such water heaters to be profitable, such need to be simple, robust, highly efficient, affordable and easy to integrate into water systems where conventional water heaters have previously been used.
Many sorption based devices work according to a batch process, which means that they operate intermittently. These sorption based devices usually include two main components: a reactor and another component that acts as either a condenser or evaporator depending on the phase of the process. In these types of devices, during a charging phase, the reactor takes in heat at high temperature and the condenser releases heat at relatively low temperatures. During the discharging phase, the reactor releases heat at low relatively temperatures and the evaporator absorbs heat at much lower temperatures. In each of these two phases, the device needs to exchange heat with the environment or ambient conditions. To supply or release heat at different temperatures using the same component as both a heat exchanger and a condenser, prior sorption based devices often use a complex system of valves, pumps, and pipes that act as an auxiliary system for the sorption device. Thus, these prior devices are typically more complex and have moving parts that result in higher electricity consumption, greater risk of leakage, and increased risk of repair or maintenance.
Accordingly, improvement is needed in sorption based devices and in water heaters using such devices.